The invention relates to cooling circuits in the casings of rotary machine and particularly to cooling passages in the casing of a gas turbine.
The casing of a rotary machine typically includes cooling passages that deliver cooling air to various locations in the machine such as inner shells of the casing and nozzles or vanes extending into a turbine or compressor. The cooling passages typically extend laterally through the casing. The cooling passages are conventionally arranged to avoid intersecting with another cooling passage. Avoiding intersecting cooling passages can limit the available positions for cooling passages and potentially result in a contorted cooling passage(s).
Ports in the casing allow bore scopes, light probes and other instruments to be inserted into the casing to inspect internal components of the gas turbine. The ports generally extend radially through the casing. The ports are positioned to avoid cooling passages in the casing. Positioning ports to avoid cooling passages and reach a desired internal position in the gas turbine can be difficult. There are many cooling passages in a typical turbine casing. The positions available for a port may be few and not aligned with regions in the turbine which should be inspected.
Because cooling passages may limit the path of other cooling passages and make difficult to position a port at certain locations on the casing, there is a long felt need for methods and apparatuses that allow greater freedom in positioning of cooling passages and ports and that ensure that cooling passages are not blocked due to intersections with other cooling passages and ports.